A very weird w810i problem

[ts013]

Do NOT flash your GDFS, your phone will be more than dead afterwards.
Try flashing MAIN and FS. If it's still messed up, try EROM flash (perhaps first with wotan, you can't do anything wrong there - it's free. click the link for instructions: EROM upgrade/fix with wotan)

[Neznam]

Do NOT flash your GDFS, your phone will be more than dead afterwards.
Try flashing MAIN and FS. If it's still messed up, try EROM flash (perhaps first with wotan, you can't do anything wrong there - it's free. click the link for instructions: EROM upgrade/fix with wotan)

I know that my question is offtopic,but can you please tell what that proces do...EROM flash?
When I need to use that?